Removable current limiting fuse



1967 M. G. LEONARD ETAL 3,

REMOVABLE CURRENT LIMITING FUSE Filed May 6', 1965 2 Sheets-Sheet 2 O 7778 y 5 79 FIG. 2.

If) no In I09 1 H4 98 FIG. 3]

I43 [3a 150 I39 United States Patent 3,345,483 REMQVABLE CURRENT LIMITWGFUSE Merrill G. Leonard, Brookfield Township, Fowler, Ohio,

and Leonard L. Wright, Sharon, Pa, assignors to Westinghouse ElectricCorporation, Pittsburgh, Pa, a corporation of Pennsylvania Filed May 6,1965, Ser. No. 453,754 6 Claims. (Cl. 200-133) This invention relates toimprovements in electrical circuit protective devices, and moreparticularly to a fuse especially suitable for use with a transformerand adapted to be mounted in a bushing extending through the wall of thetransformer housing.

Heretofore, the proper fusing of a transformer to protect thetransformer from overload or a short-circuit fault has usually requiredeither that the fuse be located at some distance from the transformer,or that the transformer housing have cover plates or other closableapertures therein so that the fuse could be reached when it wasnecessary to replace it. Neither one of these expedients represents asatisfactory solution to the problem of fusing a transformer; fusesexternal to the transformer housing require additional circuit wiringand are therefore expensive; doors in the transformer housing which mustbe opened to reach a fuse result in service difliculties, and alsoincrease the problem of hermetically sealing the transformer to protectit from moisture and other atmospheric conditions.

The removable current limiting fuse of our invention overcomes these andother disadvantages of the prior art. We provide a current limiting fusewhich is mounted inside a bore in a bushing mounted in and extendingthrough the transformer casing, one electrical connection being made tothe fuse at the inside end of the bushing, the other electricalconnection being made to the fuse at the exterior end of the bushing. Inall of the embodiments of our invention, the circuit may be broken bythe use of a hook stick to manipulate a release lever located at theouter end of the bushing, the release lever forming a part of theelectrical circuit to the adjacent end of the fuse, a spring liftexerting force against the inner end of the fuse thereafter pushing thefuse partly out of the bore in the bushing and making the end of thefuse readily accessible. In some embodiments of our invention the fuseis attached to the release lever to form a hook stick drawout, so thatcircuit may be broken and the fuse released by use of a hook stick, andthe fuse may then be drawn out by further manipulation of the releaselev-er by the hook stick.

In further summary, our invention includes a current limiting fusemounted in the bore of the bushing. One end of the bushing has a capmounted thereon; a spring withint he bore of the bushing pushes againstthe cap and exerts a force on the adjacent end of the fuse. At the otherend of the bushing, a release lever has one end hinged on a mountingbracket which is permanently secured to the bushing, and the other endof the release lever is normally held in place in a latched position bya detent mechanism, part of which is also permanently attached to theend of the bushing. The release lever has a large eye, so that a hookstick may be used to move the release lever out of the latched position,or into the latched position. In two embodiments of our invention, aweather cap secured to the release lever substantially seals or coversthe bore opening in the adjacent end of the bushing when the releaselever is in its latched position. The weather cap may have a bossextending therefrom which exerts pressure on the adjacent end of thefuse to force it inward against the tension of the aforementionedspring. In another embodiment, the adjacent end of the fuse has a studor arm extending therefrom with a *bore therein into which passes a bossor pin extending from the release lever, so that when the release leveris moved upward or away from the bushing it draws the fuse with it. Instill anothr embodiment of our invention an expansion collar composed ofrubber or other resilient material, located adjacent the end of the fusewhich adjoins the release lever, is expanded by an inwardly extendingmember attached to the release lever, the outer wall of the collar afterexpansion pressurally engaging the inner wall of the bore in thehousing. In a fourth embodiment of our invention, an O-ring effectivelyhermetically seals the space within the bushing bore.

Accordingly, a primary object of our invention is to provide new andimproved current limiting fuse apparatus especially suitable for usewith a transformer.

Another object is to provide a new and improved fuse adapted to bemounted in a bore in a bushing and adapted to be withdrawn by the use ofa hook stick.

Another object is to provide a new and improved fuse suitable formounting in a bore in a bushing and having means for sealing the borewhile the fuse is disposed therein.

These and other objects will become more clearly apparent after a studyof the following specification, when read in conjunction with theaccompanying drawings, in which:

FIGURE 1 is a cross-sectional view of a fuse and bushing according toone embodiment of our invention;

IG. 2 is a fragmentary sectional view of a fuse and bushing according tothe preferred embodiment of our invention;

FIG. 3 is a fragmentary sectional view of a fuse and bushing accordingto a third embodiment of our invention; and

FIG. 4 is a fragmentary sectional view of a fuse and bushing accordingto a fourth embodiment of our invention.

Reference is made now to the drawings, in which like reference numeralsare used throughout to designate like parts. Paying particular attentionto FIG. 1, a bushing generally designated 10 has a bore 11 extendingtherethrough, the bushing being threaded at 12 on the exterior surfacethereof and being mounted in an aperture 13 in a transformer tank 14.Near the inner or lower end 15 of the bushing there is an annular groove16 in the outer wall thereof, and disposed over the end 15 of thebushing is a cap 17 having an annular ridge or tongue 18 which fits inthe aforementioned groove 16 and retains the cap in position on the endof the bushing.

An elongated fuse generally designated 20 is disposed in the bore 11,the fuse 20 having a tube 21 of insulating material and caps or ferrules22 and 23 of conductive material. A spring 25 is disposed in the bore 11between the lower cap 23 and the inside wall of the cap 17.

Lead or conductor 26 is connected to the aforementioned cap 17 and issecured thereto as by soldering.

The other or outer end 28 of the bushing has an annular groove 29 in theouter wall thereof, and mounted upon the end 28 of the bushing is ashort sleeve 31 having an annular tongue or ridge 32 extending into thegroove. The sleeve 31 has an arm 41 on one side of the bushing; mountedthereon and if desired formed integrally therewith and extending in adirection parallel to the axis of the bushing is a terminal postgenerally designated 34 having two parallel arms, one of the arms beingshown at 39, the other of the arms not being shown for convenience ofillustration, the arms being spaced from each other and having pin 38extending therebetween, the end of the release lever 36 having a bore 40therethrough and being hinged about the pin 38 extending between the twoarms of the terminal post.

Preferably diametrically opposite to the aforementioned terminal post 34and arm 41 is an additional arm 42, extending from the sleeve 31, arm 42having two spaced upright portions, one of these upright portions beingshown at 43, having a detent at 45 cooperating with a properly surfacedarea on the aforementioned release lever 36 to form a latch. Releaselever 36 is seen to have a wide portion 47 with an eye 48 therein.

It is seen that the release lever 36 has a relatively pointed end 49which may, with adjacent spaced conductive member 50 connected to ground46, form a spark gap 51.

On the underside of the aforementioned release lever 36 there isdisposed a weather cap 53 which may be composed of conductive material,and which has a boss or protruding portion 54 of conductive materialcentrally thereof, which presses against the cap 220i the fuse, and hasan overhanging lip portion 55 which, while the release lever 36 is inthe position shown very snugly fits the endof the bushing and for allpractical purposes closes, or forms a seal or cover for the boretherein. The

electrical circuit to fuse cap 22 includes boss 54, lever 36, post 34and lead 37.

In the operation of the apparatusrof FIG. 1, assume that the currentlimiting fuse generally designated 20 has opened the circuit because ofa fault current or a sustained overload. The eye 48 of the release lever36 is then grasped by a hook stick or other convenient means and movedupwardly as seen in the figure, the right-hand end of the lever 36hinging about the pin 38, and the lever 36 may be-moved to asubstantially vertical position, in which position the fuse 20'isreadily withdrawable from the bore 11 in the bushing past the releaselever. When the arm 36 is raised, the spring 25 forces/the fuse upwardlymaking it easy to grasp the upper end of the fuse and remove it from thebore 11. After a new fuse is inserted, movement of the lever arm 36downward causes the protruding portion 54 to press against the cap 22 ofthe new fuse, the new fuse is forced down against the tension of spring25 forming a secure electrical circuit between the leads 26 and 37, andthe lever arm 36 is thereafter latched at detent 45.

Particular reference is made now to FIG. 2, in which a second embodimentof the invention is shown. In 'FIG. 2, the bottom portion of the fuseand bushing assembly, not shown, may be substantially similar to that ofFIG. 1. The short sleeve 31' is seen to have a terminal post 64 whichhas an inwardly extending boss or lip portion 65, with a flat undersurface curving as shown. Lead 61 is connected to post 64. A releaselever 66 has the right-hand end 67 thereof fitting underneath the lipportion 65, and end 67 is held snugly against the portion by thepressure of spring 25, not shown for convenience of the illustration,when end 69 of the release lever 66 is latched at detent in upright 63.The release lever 66 has two pins extending from the sides thereof, oneof these pins being shown at 76. It is seen that secured to the uppercap or ferrule 22' of fuse 20' are two arms, one of these arms beingshown at 77, the arm having an aperture 78 therein through which the pin76 passes. The weather cap 79 as before closes or covers the upper endof the bore 11 in the bushing while release lever 66 is in the latchedposition shown.

In the operation of the apparatus of FIG. 2, assuming that the fusegenerally designated 20 has opened the circuit, the eye 68 in wideportion 71 of the lever 66 is grasped as by a hook stick and raisedupwardly. End 67 of lever arm 66 moves away from the adjacent portion 65of post 64, and the arm 77 is carried with pin 76, carrying with it thefuse 20. A new fuse may be attached to the release lever 66 andthereafter the entire assembly inserted in the bore in the bushing, theend 67 of lever 66 being thereafter hooked under lip 65, and the end 69of lever 66 thereafter being brought down to secure the catch at detent75, an electrical circuit being formed between leads 26 and 61 throughthe fuse.

Particular reference is now made to FIG. 3, where a third embodiment ofthe invention is shown. Bushing has bore 91 therethrough in which a fuse92 having an upper terminal cap or ferrule 93' is located. The lower endof the fuse, spring 25- and cap 17 are not shown for convenience ofillustration. A sleeve 95 secured to the end of the bushing by thetongue and groove arrangement shown has oppositely extending arms 96 and97, arm 97 having two upright posts extending therefrom, one of theseposts being shown at 98, the other post not being shown for convenienceof illustration, and at the upper end of the post 98 is a cross bar 99extending between the posts. Lead 94 is connected to arm 97.

A release lever 102 has the right-hand end thereof shaped as at 103 toform with the bar 99 a combined catch and pivot point. Lever 102 hasportion of enlarged width 107 with eye 108 therein. End 109 of lever 102is arranged to cat-ch or latch with the detent 105. Extending from thelower side of the release lever 102 is an arm 110 having a plungerportion of enlarged diameter 111 which, when the lever 102 is presseddown in the position shown, passes partially into the central apertureor bore 112 of a resilient member or expansion collar 113, forcing theouter surface of resilient member 113 into firm engagement with theinner wall of bore 91 at or near the end of the bushing. Resilientmember 113 is secured as by cement or other suitable means, not shown,to the cap or ferrule 93 of fuse 92.' The resilient member 113 has aplate 114 of conductive material on the top thereof with an extendedstud 115 of conductive material; the upper end of the stud 115 forms apivot point for the release lever 102, and also provides a means-bywhich force is transmitted from lever 102 to fuse 92 to force the fuseinto the bore 91 against the tension of spring 25. Lead 118 passingthrough bore 119 in expansion collar 113 electrically connects ferrule93- to stud 115.

In the operation of the apparatus of FIG. 3, assume that the fuse 92 hasblown because of some overcurrent or fault condition, then the eye 108of release lever 102 is grasped as by a hook stick and moved outward andupward. Pressure retains the plunger portion 111 firmly in the bore 112in expansion collar or resilient member 113, carrying the fuse with itas the lever 102 is moved upward response to motion of the hook stick.The aforementioned end 103 of lever 102 slides underneath the cross bar99 so that the entire lever'102 with the fuse 92 attached may bewithdrawn from the bushing. Upon inserting a new fuse, the fuse isdropped into place in the bore 91, the end 103 of lever 102 is hookedunder the bar 99, and thereafter downward motion of the hook stickcaught in eye 108 moves the end 109 of lever 102 to a latching positionin detent 105. The electrical circuit to ferrule 93 'is made by way oflead 118, plate 114, stud 115, leverarm 102, cross bar 99, post 98 tolead 94.

Expansion collar 113 forms a substantially hermetical seal for the endof bore 91. 7

Particular reference is made now to FIG. 4 where a fourth embodiment ofthe invention is shown. In FIG. 4, bushing 128 has a sleeve 1129 on theend thereof with an arm 130 having a post portion 131 with detent 132.The bore 134 in bushing 128 has a portion 135 of enlarged diameter atthe end thereof in which is mounted and secured a collar 136 having anupwardly extending hook portion 137 with an overhanging lip portion 139,the lip portion 139 engaging end 142 of release lever 143, release lever143 having portion of enlarged thickness 144 with eye 145 therein. Thefuse 146 has an upper cap 147 with at least one upwardly extending armor post 148 having an aperture 149 through which passes a pin 150secured to release lever 143. The aforementioned collar 136 has anannular groove 152 on the inside surface thereof in which is disposed anO-ring 153 forming sealing engagements with collar 136 and ferrule 147.In FIG. 4, the lower ends of the fuse 146 and bushing 128, together withspring 25, are not shown for convenience of illustration.

Lead 141 is connected to collar 136 which is composed of conductivemate-rial.

In the operation of the apparatus of FIG. 4, the fuse 146 while inposition in the bore 134 is held against the tension of spring 25 by theforce which pin 150 exerts upon arm 148. Sealing is provided by theO-ring 153 in groove 152. After the fuse 146 blows, the release lever143 is grasped by hook stick in eye 145 and lifted upward carrying withit the arm 148 and the fuse 146. To reinsert a new fuse, the fuse isdropped into the bore 134, end 142 of lever 143 is hooked under lip 139,and thereafter force at eye 145 moves the end 159 of the lever downwarduntil the lever arm is latched at the detent 132.

The term pivot means as employed in the claims appended hereto is usedgenerically to designate the pin 38 and bore 40 arrangement of FIG. 1,the lip 65 and lever end 67 arrangement of FIG. 2, the cross bar 99 andshaped lever end 103 arrangement of FIG. 3, and the lip 139 and shapedlever end 142 arrangement of FIG. 4.

Whereas we have shown and described our invention with respect to someembodiments thereof which give Satisfactory results, it should beunderstood that changes may be made and equivalents substituted withoutdeparting from the spirit and scope of the invention.

We claim as our invention:

1. Releasable fuse apparatus including in combination a bushing having abore therethrough, a collar extending from one end of the bushing,spring means at one end of the bushing disposed in the bore for pressingthe fuse partially out of the bore at the other end of the bushing whenthe fuse is released, movable release lever means operatively connectedto said other end of the bushing and adapted to maintain the fuse in thebore in the bushing against the tension of the spring means, and meanscooperating with the release lever means and the bushing forsubstantially closing the adjacent end of the bore while the fuse is inits normal position in the bore in the bushing, said collar having anannular groove on the inside surface thereof, the fuse having a cap ateach end thereof, and an O-ring composed of resilient material disposedpartially in said groove and effecting a seal between the collar and theadjacent cap of the fuse.

2. Releasable fuse apparatus including in combination a bushing having abore therethrough, a fuse mounted in said bore, spring means at one endof the bushing disposed in the bore for pressing the fuse partially outof the bore at the other end of the bushing when the fuse is released,movable release lever means operatively connected to said other end ofthe bushing and adapted to maintain the fuse in the bore in the bushingagainst the tension of the spring means, means cooperating with therelease lever means and the bushing for substantially closing theadjacent end of the bore while the fuse is in its normal position in thebore in the bushing, an expansion collar secured to the end of the fuseadjacent the release lever means, the expansion collar having an axiallyextending passageway therethrough, stud means mounted upon the expansioncollar and forming a pivot point for the release lever means, and aplunger member secured to the release lever means and extending into thecentral aperture of the expansion collar, the release lever meansforcing the plunger into the aperture and forcing the outer wall of theexpansion collar against the inner wall of the bore to form a seal forthe bore in the bushing.

3. Fuse apparatus comprising, in combination, a bushing having an axialbore therethrough, a fuse disposed in said bore, terminal means at oneend of the bushing, spring means disposed in the bore exerting a forcebetween the terminal means and the adjacent end of the fuse and normallytending to force the fuse partially out of the bore in the bushing,pivot means mounted on the other end of the bushing, a movable releaselever operative-1y connected to the last-named end of the bushing andpivoting about the pivot means, latching means for holding the releaselever in a position whereat the fuse is maintained in the bore in thebushing against the force of the spring means, a collar on said bushingat the end thereof adjacent the latching means, said collar having anannular groove therein, and an O-ring located in said groove andpressing against the adjacent end of the fuse.

4. Fuse apparatus comprising, in combination, a bushing having an axialbore therethrough, a fuse disposed in said bore, terminal means at oneend of the bushing, spring means disposed in the bore exerting a forcebetween the terminal means and the adjacent end of the fuse and normallytending to force the fuse partially out of the bore in the bushing,pivot means mounted on the other end of the bushing, a movable releaselever operatively connected to the last-named end of the bushing andpivoting about the pivot means, latching means for holding the releaselever in a position whereat the fuse is maintained in the bore in thebushing against the force of the spring means, resilient means attachedto the fuse, and means carried by the release lever for forcing theresilient means into firm engagement with the inner wall of the bore toseal the bore in the bushing.

5. Fuse apparatus comprising in combination, a bushing having a boretherethrough, an elongated fuse disposed in the bore, spring meansdisposed in the bore at one end thereof and normally urging the fuse outof the bore, release lever means at the other end of the bushing adaptedto be grasped by a hook stick, means securing the release lever means tothe fuse whereby when the release lever means is moved in response tomotion of the hook stick, the release lever means carries the fuse withit, the fuse having resilient means on the end thereof adjacent therelease lever means, the release lever means carrying means adapted toengage the resilient means and carry the fuse with the release levermeans when the release lever means moves.

6. Fuse apparatus comprising, in combination, a bushing having a boretherethrough, an elongated fuse disposed in the bore, spring meansdisposed in the bore at one end thereof and normally urging the fuse outof the bore, release lever means at the other end of the bushing adaptedto be grasped by a hook stick, means securing the release lever means tothe fuse whereby when the release lever means is moved in response tomotion of the hook stick the release lever means carries the fuse withit, the release lever means having at least one pin extending from theside thereof, the fuse having an arm extending therefrom with anaperture therein adapted to cooperate with the pin, whereby movement ofthe release lever means carries the fuse with it.

References Cited UNITED STATES PATENTS H. B. GILSON, Assistant Examiner.

BERNARD A. GILHEANY, Primary Examiner,

1. RELEASABLE FUSE APPARATUS INCLUDING IN COMBINATION A BUSHING HAVING ABORE THERETHROUGH, A COLLAR EXTENDING FROM ONE END OF THE BUSHING,SPRING MEANS AT ONE END OF THE BUSHING DISPOSED IN THE BORE FOR PRESSINGTHE FUSE PARTIALLY OUT OF THE BORE AT THE OTHER END OF THE BUSHING WHENTHE FUSE IS RELEASED, MOVABLE RELEASE LEVER MEANS OPERATIVELY CONNECTEDTO SAID OTHER END OF THE BUSHING AND ADAPTED TO MAINTAIN THE FUSE IN THEBORE IN THE BUSHING AGAINST THE TENSION OF THE SPRING MEANS, AND MEANSCOOPERATING WITH THE RELEASE LEVER MEANS AND THE BUSHING FORSUBSTANTIALLY CLOSING THE ADJACENT END OF THE BORE WHILE THE FUSE IS INITS NORMAL POSITION IN THE BORE IN THE BUSHING, SAID COLLAR HAVING ANANNULAR GROOVE ON THE INSIDE SURFACE, SAID COLLAR HAVING AN ANNULARGROVE ON THE INSIDE AND AN O-RING COMPOSED OF RESILIENT MATERIALDISPOSED PARTIALLY IN SAID GROOVE AND EFFECTING A SEAL BETWEEN THECOLLAR AND THE ADJACENT CAP OF THE FUSE.